Space PhysicsTopic Summary
Topic Summary: Red Shift and Big Bang
Part of Red Shift & Big Bang — GCSE Physics
This topic summary covers Topic Summary: Red Shift and Big Bang within Red Shift & Big Bang for GCSE Physics. Revise Red Shift & Big Bang in Space Physics for GCSE Physics with 13 exam-style questions and 12 flashcards. This topic appears regularly enough that it should still be part of a steady revision cycle. It is section 14 of 14 in this topic. Use this topic summary to connect the idea to the wider topic before moving on to questions and flashcards.
Topic position
Section 14 of 14
Practice
13 questions
Recall
12 flashcards
Topic Summary: Red Shift and Big Bang
Key Terms
- Red shift — wavelength increases, galaxy moving away
- Doppler effect — wave change due to relative motion
- CMBR — 2.7 K microwave radiation from all directions
- Big Bang — origin of universe 13.8 billion years ago
- Hubble's Law — velocity proportional to distance
- Absorption spectrum — dark lines used to measure red shift
Evidence for Big Bang
- Red shift: galaxies moving away, universe expanding
- More distant = greater red shift = faster recession
- CMBR: predicted then discovered, from all directions
- CMBR temperature: about 2.7 K
- Correct H/He abundance predicted by Big Bang nucleosynthesis
Key Distinctions
- Red shift: longer wavelength, galaxy receding
- Blue shift: shorter wavelength, galaxy approaching
- Andromeda: blue-shifted (coming towards us)
- Space expands — galaxies carried with it, not through it
- Big Bang: created space itself, not explosion in space
CMBR Key Facts
- Temperature: approximately 2.7 K
- Detected from all directions equally
- Cooled-down afterglow of hot early universe
- Predicted before it was discovered (1965)
- Originally high-energy photons, now stretched to microwaves